1. Field of the Description
The present invention relates, in general, to fabrication of three dimensional (3D) objects, and, more particularly, to a method of using a 3D printer (and corresponding 3D objects) to print 3D objects that can be used to limit unpermitted or non-licensed copying.
2. Relevant Background
3D printing is an additive technology in which objects (or “printed 3D objects”) are created from a digital file. The digital file may be generated from software such as a computer aided design (CAD) program or another 3D modeling program or with a 3D scanner to copy an existing object that provides input to a 3D modeling program. To prepare the digital file for printing, software, provided on a printer-interfacing computer or running on the 3D printer itself, slices the 3D model into hundreds to thousands of horizontal layers. Typically, only the outer wall or “shell” is printed to be solid such that a shell thickness may be defined as part of modifying the 3D model for use in printing, and, during printing, the shell is printed as a solid element while the interior portions of the 3D object are printed in a honeycomb or other infill design (e.g., to reduce the amount of material that has to be printed to provide the printed 3D object).
When the prepared digital file of the 3D object is uploaded into the 3D printer, the 3D printer creates the object layer-by-layer. The 3D printer reads every slice (or 2D image) from the 3D model and proceeds to create the 3D object by laying down (or “printing”) successive layers of material until the entire object is formed. Each of these layers can be seen as a thinly sliced horizontal cross section of the eventually completed or printed 3D object.
One of the more common 3D printer technologies uses fused deposition modeling (FDM) or, more generally, fused filament fabrication (FFF). FDM printers work by using a plastic filament (e.g., acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) provided as strands of filament that is 1 to 3 millimeters in diameter) that is unwound from a coil or spool mounted onto the printer housing. The plastic filament is used to supply material to a print head with an extrusion nozzle, e.g., a gear pulls the filament off the spool and into the extrusion nozzle. The extrusion nozzle is adapted to turn its flow on and off. The extrusion nozzle (or an upstream portion of the print head) is heated to melt the plastic filament as it is passed into, or through, the extrusion nozzle so that it liquefies. The pointed extrusion nozzle deposits the liquefied material in ultra fine lines (e.g., in lines that are about 0.1 millimeters across).
The extrusion head and its outlet are moved in both horizontal and vertical directions to complete or print each layer of the 3D model by a numerically controlled mechanism that is operated or controlled by control software running on the 3D printer (e.g., a computer-aided manufacturing (CAM) software package adapted for use with the 3D printer). The extruded melted or liquefied material quickly solidifies to form a layer (and to seal together layers of the 3D object), and the extrusion nozzle is then moved vertically prior to starting printing of the next layer. This process is repeated until all layers of the 3D object have been printed. The print surface, which may be called a print bed or build plate, is often heated also to avoid having the bottom layer of plastic of the 3D object delaminating during printing.
The increased availability and widespread use of 3D printers has generated a number of new problems. For example, 3D printed objects are very easy to reproduce or copy. Copies of a 3D object may be produced by transferring or sharing the digital file that was used to produce the first of a particular 3D object. In other cases, a 3D object may be scanned to produce a new digital file that can be used to control a 3D printer to reproduce a 3D object that exactly, or nearly so, copies all of the external features of the scanned 3D object. As a result, it presently is a rather trivial task for one in the possession of a 3D printer to produce unlimited identical copies of a printed object (or printable model) either by obtaining the 3D model or creating their own.
As can be seen, 3D printer and related technologies including scanners have made it very difficult to prevent copying of many products or objects, and it is difficult to impossible presently to distinguish between an original 3D printed object and a later printed copy. Such accurate copying can be particularly troubling in the field of collectables. A collectable manufactured for sale to collectors as collectables is often more valued by their owners when they have a proven authenticity as coming from a particular source or are part of a limited run. For example, a collector may seek out a figurine of a character from a live or animated film when they can readily verify that the figurine (or “3D object”) is one of a limited run produced by a particular company (e.g., the figurine is Figurine No. 45 of a run of 1000) after which the “mold” is not used to produce more figurines. If these figurines can be easily copied with a 3D printer, though, the uniqueness and desirability of these figurines may be significantly reduced.
Hence, there remains a need for a technique for preventing unpermitted or unlicensed copying of 3D objects. Such a copying-prevention technique preferably would be useful to block or limit the use of 3D printer technologies to print a copy of a particular 3D object, which will allow people to continue to be assured they are acquiring an original print of a model and may also allow collectors to validate that their product (or 3D object) is authentic.